JPS5991514A - Control system for stopping main shaft in home position - Google Patents

Abstract

PURPOSE:To shorten the stop control time, by switching the mode from a speed control mode to a position control mode while keeping the speed at the time when a main shaft home position stop command is inputted. CONSTITUTION:In the state of a normal speed control of a main shaft 4, the contact of a changeover switch 8 is connected to a side (a), and data is inputted to a speed control circuit 1 to perform the normal speed control. A length required for stopping the main shaft 4 in an instructed stop position after deceleration from an actual speed VACT is operated preliminarily in a main shaft home position stop control circuit 10 on the basis of the actual speed VACT and a speed error constant Kv of the main shaft 4 to obtain a deceleration start position; and when a main shaft home position stop command MC is inputted, the changeover switch 8 is switched to a side (b) by a switching signal CHG simultaneously with passing of the rotation position of the main shaft 4 through the deceleration start position, and a motor 2 is stopped in a prescribed position.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a main spindle fixed position stop command system for positioning a main spindle of a machine tool or the like to a predetermined position in the shortest possible time.

Figure 1 shows an example of a conventional spindle fixed position stop control device, in which the speed control time ``%i'' is determined by the motor 2 for driving the spindle 4.
The speed output V of the tacho generator 3 as a speed detector connected to the motor 2
A and CT are fed back to the speed control circuit 1. The motor 2 also has a main shaft 4 composed of gears, pulleys, etc.
A speed change mechanism 5 is connected to the main shaft 4, and a pulse encoder 6 as a position detector for detecting the rotational position of the main shaft 4 is connected, and the pulse signal APA from the pulse encoder 6 controls the main shaft fixed position stop control. It is input to circuit 7. A changeover switch 8 is provided at the input section of the speed control circuit 1. A speed command voltage VCON is inputted to the contact a of the changeover switch 80 from a speed command circuit (not shown), and the contact a is connected to the main shaft fixed position. The output DIF from the stop control circuit 7 is input, and the contacts a and b are switched from contact a to contact S when the main shaft fixed position stop command MC is input.

In such a configuration, the operation will be explained with reference to the timing charts of FIGS. 2(A) to 2(C). In the speed control mode, the changeover switch 8 is connected to the contact a side, The command voltage VCON is inputted to the speed control circuit 1 as a command signal S (FIG. 2(B)), thereby driving the motor 2 to rotate.

The motor 2 rotates the main shaft 4 via the speed change mechanism 5, and its speed is measured by the tachogenerator 3 and fed back to the speed control circuit 1, so the speed control circuit 1 adjusts the speed command voltage VCON (VB). The rotation of the motor 2 is controlled so that the difference from the actual speed VACT becomes zero, thereby obtaining the desired speed (■1). In this speed control state, as shown in FIG. )
When a spindle fixed position stop command MC as shown in (
At time B), the changeover switch 8 is switched from contact a to b, and a low speed indexing speed command voltage DIF as shown in FIG. The speed decreases (Figure 2 (C)).

When the actual speed reaches v2 (time point 12), the spindle 4 is rotated to the rotational position (for example, 90° or 120° before the spindle stop position) at which position closed loop control is started at that speed v2. After this position (time point i3), the spindle fixed position stop control circuit 7 inputs a voltage corresponding to the deviation between the commanded stop position and the actual position to the speed control circuit 1 via the changeover switch 8, so that the position deviation becomes zero. Position control is performed so that the main shaft 4 is stopped at a predetermined position.

This will be explained according to the rotation explanatory diagrams of the main shaft 40 shown in FIGS. The point S is stopped at the stop position O of the fixed part 41. Point P of the fixed FA 41 is the starting point for switching from the speed control mode to the position control mode, and the position control mode is started when the rotation part reference point S of the rotating part 420 reaches this point P. . That is, the second
At time t2 in the figure, if the S point of the rotating part 42 reaches the area AK, the reference S point rotates at a constant speed 2 until the P point, and when it reaches the P point (time t3), the position is controlled. Switch to mode and stop at 0 point. However, if the reference point S is in the area BK at time t2, the S point will not stop at the 0 point (it will continue to rotate and only start the position control mode when it reaches the P point at time t3). death,
This is so that it stops at the 0 point.

In such a conventional spindle fixed position stop control system, when the actual speed decelerates from the normal speed 1 to the indexed speed 2, the rotational position when reaching speed 2 starts the position ηi control. b) If you have already passed position CP),
Position control start value 1 "f:c (P
), which requires a maximum of 1/2 time, and this dead time remains constant no matter what speed the spindle is stopped at a fixed position. There is. Due to the occurrence of such dead time, there is a drawback that the stopping operation of the spindle is delayed. Therefore, an object of the present invention is to shorten such dead time (C).

This invention is described below.

This invention has a speed feedback loop, which controls the rotation of the spindle motor according to the given command speed VCONK, and when the spindle fixed position stop command MC is input,
This relates to a spindle fixed position stop control system that detects the rotational position of the spindle 4 driven by the spindle motor 2 and stops the spindle 4 at a fixed position according to the deviation from the commanded stop position. As shown in Figure 4, the actual speed VACT of the main shaft 4 and the speed error foot count K during speed control j
The spindle fixed position stop control circuit 10 calculates the deceleration start position in advance by calculating the distance required to decelerate from the actual speed VACT and stop at the commanded stop position f using v, and then calculates the deceleration start position from the spindle foot position stop command NC. When input, at the same time as the main shaft 4 passes through the rotational position or deceleration start position, the switching signal cHG is activated.
By switching the contacts of the changeover switch 8,
It is designed to switch to position control mode and stop at a fixed position. Further, the configuration of the spindle fixed position stop control circuit 10 is exactly as shown in FIG.
and a multiplier circuit 11 that calculates the rotational distance DEC required to stop at a fixed position from the reciprocal of the speed error constant IgV of the servo system, and a multiplication circuit 11 that calculates the rotational distance DEC required to stop at a fixed position from the reciprocal of the speed error constant IgV of the servo system.
)), and the main 11!11I4.
Each time the rotation reference position S passes the stop position O, the main shaft 4
Set the number of pulses per spindle rotation of the pulse encoder 6 connected to When MC is input, the fraction α and the output value L of the down counter 13
A comparison circuit 14 outputs a switching signal (1) G for switching from the speed control mode to the position control mode when the speed control mode matches the position control mode, and a rotation distance 1) EC is preset by the main shaft constant position stop command MC. , switching signal C) IG
A preset down counter 15 that sequentially subtracts the generated pulse APA when APA is output, and a DA converter 16 that converts the output value of the preset down counter 15 into an analog signal and uses it as an index position deviation analog voltage DIF. It consists of In addition, here, pulse encoder 6
is designed to generate a total of 1 pulses per 401 rotations of the main shaft, and the speed error constant Kv of the servo system
is determined by the inertia of the main shaft 4, the gain of the speed control circuit 1, etc.

Furthermore, the fraction extraction circuit 12 outputs the output DEC of the multiplication circuit 11.
For example, if the rotation is 5.3 rotations, the down counter 13 outputs a value (α) that corresponds to 0.3 rotations, and the down counter 13 outputs a value (α) corresponding to 0.3 rotations.
Each time the count value is generated, one value is subtracted from N, and when the count value reaches 0, it is reset and subtracted from N again.

In such a configuration, its operation is shown in FIGS.
The operation will be explained with reference to the timing chart of C).

First, when the main shaft 4 is under normal speed control, the contact of the changeover switch 8 is connected to the a side, and the speed command voltage VCON from the speed command circuit is input to the speed control circuit 1, and the above-mentioned Such speed control is performed. At the same time, the multiplication circuit 11 in the spindle fixed position stop control circuit 10
is the deceleration distance DE required to perform position control and stop at the stop position O shown in FIG.
Find C. If the value of this deceleration distance DEC is, for example, 5.3 rotations, then the fraction α when the 8 points start the position control mode is the value of 0.3 rotations (
angle), and this fraction α is extracted by the fraction extraction circuit 12.

(time tl), the recent down counter 15 presets the deceleration lid DEC obtained by the multiplier 10 circuit J1, and the comparison circuit 14 compares the fraction α obtained by the fraction extraction circuit 12 with the output value LS of the down counter 13. Compare (・, the rank during one rotation between time 11 and t2: '1lj
Find lJ starting position V1-, and when both match, switch signal (='1-(G is applied 113 times (6th part 1 (C))
. This changeover signal C)1G causes the contact of the changeover switch 8 to be switched from a, 0tjj to the b side (time 12), and at the same time, the recent rerun counter 5 causes the pulse encoder 6 to generate a pulse A1'A1. As a result, the output Di of the A converter 16
A voltage proportional to the rotational distance is supplied to the speed circuit 1.

That is, the down counter 13 is set to L)EC when the 8 points in FIG.
Counted down by A K, E 31m (13)
When the rotation position is reached, the value becomes α (for example, 0.3 rotations). Therefore, at this time, the comparator circuit 14 outputs a switching signal CJ'G which is a matching signal between the two, and the deceleration distance 1)EC set in the preset down counter 15 is
(for example, 5.3 rotations), and when the count value of the preset down counter 15 reaches 0, the S point eventually matches the 0 point. This makes it possible to accurately position the 8 points to the 0 point. Ru.

As described above, according to the present invention, when the spindle fixed position stop command is input, it is possible to switch from the control mode to the position control mode while maintaining the same speed as when the spindle fixed position stop command is input.
Compared to the method where the firewood is allowed to stagnate at low speed and then switched, the dead time can be significantly shortened. In addition, in the conventional device 11' shown in FIG.
~200 to 1, the time required to stop is about 4 to 5 seconds, or according to this discovery] 3 to 4 seconds and about 1
It became clear that it would happen in seconds.

[Brief explanation of the drawing]

1 is a block diagram showing an example of a conventional spindle foot position stop control device, FIGS. 41st diagram to explain the state of localization f6 stop control
g+ is a block diagram showing one embodiment of the present invention, Fig. 5 is a block diagram showing an example of the configuration of a three-axis foot position control circuit according to the present invention, and Figs. 6 (A) to (C) are its operation. 5 is a timing chart showing an example. 1...Speed? 1ifJ control circuit, 2... motor, 3...
...Tachometer generator, 4...Main shaft, butt...Transmission mechanism, 6...Pulse encoder, 7, 10...Main shaft positioning 11 peaks-stop control circuit, 8...Switch-over switch, 11...
. . . Multiplication circuit, 12 . . . Fraction extraction circuit, ] 3 . . . Down counter, 14 .

Claims (1)

[Claims] 1. A speed feedback loop, which controls the rotation of the spindle motor according to a given command speed, and controls the rotation of the spindle driven by the spindle motor when a spindle fixed position stop command is input. In a spindle fixed position stop control method that detects the position and stops the spindle at a fixed position according to the deviation from the commanded stop position, the spindle is decelerated from the actual speed according to the actual speed of the spindle and a speed error constant in speed control. The deceleration start position is determined by calculating the distance required to stop at the commanded stop position, and when the spindle fixed position stop command is input, the rotational position of the spindle passes through the deceleration start position and the position is A spindle foot position control system, characterized in that the spindle is stopped at the fixed position by switching to a control mode. 2. It has a speed feedback loop, which controls the rotation of the spindle motor according to the given command speed, and when a spindle fixed position stop command is input, detects the rotational position of the spindle driven by the spindle motor and outputs the command. In a main spindle fixed position stop control device that stops the main spindle at a fixed position according to a deviation from a stop position, a speed feedback signal forming the speed feedback loop and a reciprocal of the speed error foot of the servo system until the main spindle stops at the fixed position. a multiplier circuit for calculating the rotation distance required for the rotation distance; a fraction extraction circuit for extracting a fraction from the rotation distance; and a main shaft 1 of a pulse encoder connected to the main shaft each time the rotation reference position of the main shaft passes the fixed position. Set the number of pulses for the rotation roar,
A down counter that subtracts the generated pulses from the pulse encoder from the number of pulses and when the spindle fixed position stop command is input, compare the fraction and the output value of the down counter, and when they match, the speed is determined. a ratio soft circuit that outputs a switching signal for switching from the control mode to the position control mode; and a ratio soft circuit that presets a rotational distance required for the spindle to stop at the fixed position according to the main shaft fixed position stop command, and outputs the switching signal. It is characterized by being equipped with a preset down counter that sequentially subtracts the generated pulses at the same time, and a DA converter that converts the output value of this preset down counter into an analog signal and uses it as a command position signal. Stop control device.